The central aim of this project is to determine how linguistic intentions are instantiated in motor actions and how motor and representational factors are related to language disorders. Specific language impairment (SLI) is a disorder that affects approximately 7 percent of children at the time they enter kindergarten. Because of the longstanding adverse academic, social, and communicative consequences of SLI, it is imperative to understand the bases of the disorder for the development of appropriate intervention strategies. Many current approaches to SLI focus entirely on language factors. However, language is expressed through movement, and deficits in motor skill have also been implicated in children with SLI. In both normal and disordered development, an important aspect of the developmental process is the linking of motor output patterns with emerging linguistic representations. A major hypothesis underlying this work is that, because linguistic and motor capacities mature at different (and protracted) rates, during development there is a complex bi-directional interface between language and motor processes. In the present research the primary language-motor link to be explored is the acquisition of the rhythmic structure of language, or prosody. The strategy in these studies will be to examine the development of rhythmic structure in a variety of linguistic, manual, and oral motor tasks. The experiments combine new physiological analyses of movement with existing acoustic and phonetic approaches. In the first set of experiments, the primary objective is to understand how prosodic distinctions are produced across different lexical and morphosyntactic contexts. The structure of movement and acoustic output will be examined both when children produce and when they overtly omit function and content forms (omission is a frequently observed error type for children with SLI). In a second set of experiments, the effect of linguistic processing will be removed to test if prosodic deficits are generalized across other motor systems (i.e., non-speech oral and manual movements) or are specific to the complexities of linguistic output. The results of these experiments will have important implications both for understanding how speech production processes develop and for designing appropriate intervention for children with SLI.